"I could just see one of the guys actually just attacking the porters with a bush knife.

"There was one guy with a rifle, one guy had a pipe gun and a bush knife and they would come at us.

"There was one person who appeared to be controlling it, but they would go back up to the porters and attack again and again."

Mr Bennett says he fears the senseless crime will have a terrible impact on the local community.

"We're not the story to be honest, it's what's going to happen to those villagers, to those children, to the children of those villagers and those porters who have now basically been deprived of work, who've been horrifically injured," he said.

"So it's a terrible, terrible thing."

The injured men hiked four hours back to safety, carrying the porters' bodies.

The five other Australians are from Victoria and they are due back in Melbourne.

There was one person who appeared to be controlling it, but they would go back up to the porters and attack again and again.

Nick Bennett

Melbourne man Peter Stevens from Melbourne was slashed on the leg by one of the machete-wielding attackers.

"It was a terrible experience. It was frightening," he said.

After the attack the group trekked for five hours in the direction the bandits had fled, back to the town of Wau, to get help.

Kim Dewar, who is friends with Mr Stevens and fellow Victorian Rod Clarke - says it has been a shocking ordeal for them.

She says Mr Clarke has had a long association with PNG and has a great affection for the country.

Ms Dewar says the men's wives are "exhausted with worry" but are looking forward to their husbands returning home sometime today.

Trek leader praised for attack response

Mr Stevens has praised the bravery of trek leader, Australian Christiana King.

"When these rascals sort of had us all down on the ground and things like that they were demanding who the leader was and she stood up," he said.

Mr Bennett has also paid tribute to Ms King, who he says led them to safety.

"Christie is a very, very brave woman. She's exceptional," he said.

"Without her quick thinking perhaps we wouldn't be here.

"So she did an amazing job of helping to direct them to where the money they were obviously looking for was, and assisting us to walk down a track we'd never walked before.

PNG's prime minister Peter O'Neill says those responsible for the brutal attack will face the death penalty.

Mr O'Neill says the ordeal is an "obvious setback" to efforts to promote PNG as a tourist destination.

PNG's high commissioner to Australia has described the attack as "inexcusable".

The motive for the attack is not clear, although some reports have suggested it could be related to a disagreement between porters from PNG's lowlands and locals living in the highlands.

After the Kokoda Track, the Black Cat Track is one of the most popular treks in PNG.

It is a rough track that runs from the village of Salamaua on the coast of the Huon Gulf, south into the mountains to the town of Wau.

In the wake of the attack, the Department of Foreign Affairs is advising trekkers to avoid the track until local police have investigated the incident.